Miley takes to Twitter once again to dismiss Sinead, telling her she is too busy to 'write you an open letter cause I'm hosting & performing on SNL this week'. She added: "So if you'd like to meet up and talk lemme know in your next letter. :)"

Sinead O'Connor and Miley Cyrus

Taking to Facebook to reply to Miley's latest outburst, Sinead threatened Miley with legal action, and also questioned whether she would say the same things about friend Britney Spears, who also has a history with mental illness.

"Miley, I have no interest whatsoever in meeting you," she wrote. "You had plenty of time yesterday to abuse Amanda Bynes .. an entirely innocent party.. and myself.. who also did nothing to deserve your abuse.. along with every other sufferer of mental health problems and every person who suffered abuse at the hands of priests.

"You can take five minutes today between g- string f**kin' changes to publicly apologise and remove your abusive tweets. If you do not then you don't give a shit who you mock and what damage you do by being so ignorant.

When you publicly apologise to Amanda and myself and all mental health sufferers as well as all who were abused by priests that will end the matter as far as I am concerned."

Sinead went on: "What you did yesterday was designed to damage me and my career and has caused me enormous distress and harassment and has potential to damage my career, since you deliberately gave the impression those tweets of mine were not two years old but reflect my current condition. If you cannot apologize I will have no choice but to bring legal proceedings against you since it is extremely hard to be given work when people think one is suffering from mental illness.

"I have no interest in or desire to cause you trouble but if you do not apologise for having deliberately tried to cause me hurt and trouble personally and professionally I will have to bring pressure upon you.

"When you end up in the psych ward or rehab I'll be happy to visit you.. and would not lower myself to mock you.

"Be a proper woman and make the public apologies I have listed above. Your hosting SNL is a bullshit reason for not taking five minutes to do the right thing and your behaviour yesterday will rebound upon you very badly.

"You have no business abusing Amanda Bynes or anyone else. How do you think you made her feel yesterday? How do you feel when your friend Britney Spears is mocked and humiliated for having had mental health problems? I know I personally want to bash those who treat her that way. If she is your friend and more importantly if you are a true friend to her.. you ought apologise for joining those who mock and humiliate women who have been too nice frankly, to manage the music business without sensibly losing their minds."

She added: "Cease behaving in an anti-female capacity. You will become the victim of it shortly. Soon it will be you the media 'crazy' .. and you will not enjoy it.. and you will appreciate people (like myself) standing up for you. Which I will be happy to do.. if you earn my respect today by apologising publicly."

Why do we get the feeling it's only a matter of time before Miley takes to Twitter once again?

Celebrity Feuds

Celebrity Feuds

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Lord Sugar and Tulisa

Lord Sugar didn't hold back when he tweeted Simon Cowell to tell him exactly what he thought of Tulisa on 'The X Factor', telling him: "She knows nothing and talks rubbish". She responded by calling him an "ugly hobbit" and a "miserable old man". He had the last laugh though when she was axed from the show a few months later.